Electric plug



Feb. 11, 1941. w. s, THOMAS I ELECTRIC PLUG Filed March 17, 1938 3 ww/wto'a 7457154771 5: 777071105,

Patented Feb. ll, 1941 wi l oma M to v e. P s sn n H ,:by direct and mcsne assignments, of,thirty.- one., a

andtwo-thirdsper cent to .Herbert fl.,Flook, and thirty-one twothirds per cent, 1

Hughes G. Meaker, both of Mansfield, Pas andlive per cent to Christian It. Nielsen, -Washington, D. 0.

Application March 17, 1938, Serial No. 196,551

1 Claim.

This invention relates to electric socket plugs for eflectingfirm and positive electrical contact between the prongs of the plug and the contact plates of a socket,and it consists in the constructions, arrangements and combinations herein described and claimed. 7

It is an objector theinvention to provide a plug having a novel construction of resilient contact blades for effecting positive engagement with the contact plates of a socket.

It is a further important objector the invention to provide a contact blade embodying a pair of resilient leg or blade members which normally are divergentwith respect toone another, .but movable to a substantially parailelrelation when engagedwithin a socket, thereby insuring con tact with the blades throughouttheir lengths:

It is a still further object of theinvention to provide a novel spring means interposed between the legs of the blades imparting further resilience to the legs and insuring a positive, yet releasable engagement between the legs and the contact plates of a socket- I Additional objects, advantages and features of invention will be apparent from the following description, considered in conjunction with the accompanying drawing, wherein Figure 1 is a vertical sectional view of the plug, engaged in a socket member,

Figure 2 is a plan view of the plug,

Figure 3 is a side elevation 01' the plug, partly in section, c Figure 4 is'a perspective view of one of the contact blades. I 1 I Figure 5 is a perspective view oi one of the spring members. I c

Referring to the drawing, a conventional form of socket is indicated by the reference character I 0, and as well understood, the socket IOincludes contact plates II. In some constructions I of sockets the plates I I are positioned upon the outer walls of the recesses l2, while in other forms of c the socket, the plates are located upon the inner wallsof the recesses I2, as shown in Figure l, and my plug is applicable to either construction, as will be apparent as the description proceeds.

The plug comprises a body I3 of insulating material of any approved shape, recessed as at H for accommodation of contact members generally.

indicated at I5. The contact members each embody a base portion l6 shaped to fit within the recess ll of the body and is apertured as at H for reception of a screw l9 whereby the contact member will be firmly secured to the body.

effecting a tight frictional engagement between Formed integrally with the base I6, eiitending outwardly at right angles thereto, a flat contact approximatelyon a line with the face 20 of the The contact members I5 areformed of copper in order toprovide proper conduction of electrical energy, and while such metal will have acertain inherent resilience for effecting contact with the plates ll ;of the socket, it has been found that the resilience of the blades soon become so re- 15 duced as to prevent proper contact, and in order to insure the required resilience in the blades at all times, I provide a spring 23 interposed between the blades I9 and 22.

The spring 23 will be formed from any suitable spring steel of proper gauge, and includes a foot 24, at right angles to the body 25 thereof. The foot 24 snugly rests upon the base l6 and is apertured as at 26 to receive the screw I8. It will be noted that the screw mounts the spring and base to the body of the plug.

The major portion of the body 25 of the spring abuts the blade III for a short distance and is then bowedoutwardly in the direction of and conthis, resilience to the major portion of the leg 22 willbe imparted.

In use, the plug is presented to the socket, the

blades I5 being aligned with respective recesses of the socket and forced thereinto, which action presents the blades I9 against the inner walls of the recesses I2 andthe free blades 22 against the contact plates I I. The normal divergence of the blades 22 is such that they will be flexed toward respective blades l9, against the inherent resilience oi. the blades and the spring, thereby the sides of the recesses and the contact plates I l of the socket. When the contact members I5 are fully engaged within a socket member they assume substantially a parallel relation, reducing strain upon the plastic material of the body.

' being formed of resilient conducting material and of a length projecting from the body, each blade having an integral extension divergent thereto An attachment plug comprising a body mem- I ber of insulating material, a pair of spaced flatcontact blades, each blade having a right angular base fixed within the body member, said blade and of a length stopping short of the bodymemher, the juncture of respectivefbldes and extensions forming an open bight, a fiat leaf spring in terposed between respective blades and extensions, said springs having right angular bases complemental to respective bases of the blades for-securement theretoQsaid springs being of a 6 length slightly greater than half the length of the contact blades, the springs being bowed outwardly in the direction of respective extensions 1 tending to maintain the divergent relation of. the

extensions, and said springs each terminating in arced heel portions-for slidable contacting en- 7 gagement with respective extensions of the blades at points inwardly of the biht defined by the blades and extensions.

We THOMAS; 

